Composite Surface

The Spirals example surface.

import numpy as np
import s3dlib.surface as s3d

#.. influenced by M.C.Escher - Spirals obj output
#..  https://mcescher.com/gallery/mathematical/

# 1. Define function to examine .....................................

def twisted_torus(rtz,rotate) :
    twists, width, radMax, radMin, stretch = 5, 0.125, 0.70, 0.05, 1.4
    r,t,z = rtz
    ratio = radMax - t*(radMax-radMin)/(2.0*np.pi)
    phi =t*twists + rotate*2*np.pi + np.pi/4.0
    z = width*z
    Z = ratio*np.sin(z*np.pi+phi)
    R = r + ratio*np.cos(z*np.pi+phi)
    T = t*stretch
    return R,T,Z

# 2. Setup and map surfaces .........................................

surface = None
rotation = [0.00, 0.25, 0.50, 0.75]
for i,rot in enumerate(rotation) :
    t = s3d.CylindricalSurface.grid(50,1000,'s')
    t.map_geom_from_op( lambda rtz : twisted_torus(rtz,rot) )
    if i is 0 : surface = t
    else :      surface += t

s3d.save_surfgeom_to_obj('obj_files/spirals.obj',surface)